Purana Qila

Purana Qila (Old Fort) is one the oldest forts in Delhi. Its current form was built by Sher Shah Suri, the founder of the Sur Empire. Sher Shah raised the citadel of Purana Qila with an extensive city-area sprawling around it. It is believed that the Purana Qila was still incomplete at Sher Shah's death in 1545, and was perhaps completed by his son Islam Shah , although it is not certain which parts were built by whom.

• http://en.wikipedia.org/wiki/Purana Qila